Toyota Sequoia (2005). Manual — part 92
–
DIAGNOSTICS
ENGINE
DI–171
365
3
Check air induction system (See page
CHECK:
Check the air induction system for vacuum leaks.
NG
Repair or replace air induction system.
OK
4
Perform active test (A/F control).
(a)
Connect the hand–held tester to the DLC3.
(b)
Start the engine and turn the tester ON.
(c)
Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(d)
On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST /
A/F CONTROL.
(e)
Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT
button to change the fuel injection volume).
(f)
Monitor the voltage outputs of A/F and HO2 sensors(AFS B1S1 (AFS B2S1) and O2S B1S2 (O2S
B2S2)) displayed on the tester.
HINT:
The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection
volume by 25 %.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard:
Tester Display
(Sensor)
Injection Volumes
Status
Voltages
AFS B1S1 (AFS B2S1)
(A/F)
+25 %
Rich
Less than 3.0
AFS B1S1 (AFS B2S1)
(A/F)
–12.5 %
Lean
More than 3.35
O2S B1S2 (O2S B2S2)
(HO2)
+25 %
Rich
More than 0.55
O2S B1S2 (O2S B2S2)
(HO2)
–12.5 %
Lean
Less than 0.4
Result:
Status
AFS B1S1
(AFS B2S1)
Status
O2S B1S2
(O2S B2S2)
A/F Condition and
A/F Sensor Condition
Misfires
Suspected Trouble Areas
Proceed To
Lean/Rich
Lean/Rich
Normal
C
Lean
Lean
Actual air–fuel ratio lean
May occur
PCV valve and hose
PCV hose connections
Injector blockage
Gas leakage from exhaust system
Air induction system
Fuel pressure
Mass Air Flow (MAF) meter
Engine Coolant Temperature (ECT)
sensor
A
DI–172
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DIAGNOSTICS
ENGINE
366
Rich
Rich
Actual air–fuel ratio rich
Injector leakage or blockage
Gas leakage from exhaust system
Ignition system
Fuel pressure
MAF meter
ECT sensor
A
Lean
Lean/Rich
A/F sensor malfunction
A/F sensor
B
Rich
Lean/Rich
A/F sensor malfunction
A/F sensor
B
Lean: During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the
HO2 sensor output voltage (O2S) is consistently less than 0.4 V.
Rich: During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than
0.55 V.
B
Go to step 11.
C
Go to step 15.
A
5
Read value of engine coolant temperature.
PREPARATION:
(a)
Connect the hand–held tester to the DLC3.
(b)
Turn the ignition switch to ON and turn the tester ON.
(c)
Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / COOLANT
TEMP.
CHECK:
(a)
Read the COOLANT TEMP twice, when the engine is cold and also when warmed up.
Standard:
With cold engine: Same as ambient air temperature.
With warm engine: Between 75
C and 95
C (167
F and 203
F)
NG
Replace engine coolant temperature sensor.
OK
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DIAGNOSTICS
ENGINE
DI–173
367
6
Read value of mass air flow meter.
PREPARATION:
(a)
Connect the hand–held tester to the DLC3.
(b)
Turn the ignition switch to ON and turn the tester ON.
(c)
Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / MAF and
COOLANT TEMP.
(d)
Allow the engine to idle until the COOLANT TEMP reaches 75
C (167
F) or more.
CHECK:
(a)
Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.
Standard:
MAF while engine idling: Between 1.4 gm/s and 2.3 gm/s (shift position: N, A/C: OFF).
MAF at engine speed of 2,500 rpm: Between 5.4 gm/s and 7.9 gm/s (shift position: N, A/C: OFF).
NG
Replace mass air flow meter.
OK
7
Check fuel pressure (See page
CHECK:
Check the fuel pressure (high or low pressure).
NG
Check and replace fuel pump, pressure regula-
tor, fuel pipe line and filter (See page
).
OK
8
Check exhaust system for gas leakage.
OK:
No exhaust gas leakage.
NG
Repair or replace exhaust gas leakage point.
OK
B17396
HT
+B
AF–
AF+
Sensor 1
A/F Sensor
Component Side:
Front View
DI–174
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DIAGNOSTICS
ENGINE
368
9
Check for spark and ignition (See page
).
HINT:
If the spark plugs or ignition system malfunction, engine misfire may occur. The misfire counter can be read
with the hand–held tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / MIS-
FIRE / CYL#1 (to CYL#8).
NG
Repair or replace ignition system.
OK
10
Check injector injection (See page
HINT:
If the injectors malfunction, engine misfires may occur. The misfire counter can be read with the hand–held
tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / MISFIRE / CYL#1 (to
CYL#8).
NG
Replace injector.
OK
11
Check resistance of air–fuel ratio (A/F) sensor heater.
PREPARATION:
Disconnect the air–fuel ratio (A/F) sensor connector.
CHECK:
Measure resistance between the terminals of the A/F sensor
connector.
OK:
Standard:
Tester Connection
Specified Condition
HT (1) – +B (2)
1.8 to 3.4
Ω
at 20
C (68
F)
HT (1) – AF– (4)
10 k
Ω
or higher
NG
Replace air–fuel ratio (A/F) sensor.
OK
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